Spring Start Surprise...Help Needed

[Christopher J. Bunsey]

I changed my oil/filter and fuel filter. I cranked it a few times, stepped on the gas to set the choke and wala, she started. BUT when the engine started the headlights popped open. I went in to check the switch position, and it was in the off or forward position. I pulled it out the light went on, and when I pushed it inthe lights went out, but the lids are still open. Can anyone help me diagnos the problem!!! It is a 1976.

Thanks a lot!

Chris

[Ralph S.]

Re: Spring Start Surprise...Help Needed

Sounds like the vacuum switch under the drivers side of the dashboard is pulled down keeping the lights up. Or you pulled a vacuum hose off.

[Christopher J. Bunsey]

Re: Spring Start Surprise...Help Needed

I cant find anything in the manuals to help me trace things.....I was looking for a schematic for the vacume system............ Where should I start?

[Jack H.]

Re: Spring Start Surprise...Help Needed

Vac system schematics are sold by various Corvette parts catalog houses, but your copy of the Chassis Service Manual should also provide details on the vac operated headlights...

The reason the headlight buckets are up and staying up is their being 'told' to open. The vac system has two parallel paths, servo and control. The servo side is the vac that actually moves things while the control side says when to move this/that...

The servo path for the headlights starts at the check valve in the engine compartment (aluminum disk with one input and two output nipples) where vac is taken from the small nipple and routes through the firewall into the cockpit. The headlight servo path makes two stops in the cockpit:

(1) At the headlight over-ride switch beneath the steering column (lets you force the HL buckets open to change lamps).

(2) At the headlight switch.

The truth table is simple if either switch (or both) vents vac (a loose hose connection will also vent vac), the headlights buckets open.